The present invention relates to a system for releasing bleach into a wash from a bleach precursor found in the wash (e.g., a diacyl peroxide) using enzymes as activators of the bleach precursors.
Various bleaches have long been employed in numerous cleaning applications including the washing and prewashing of fabrics as well as in other applications such as hard surface cleaning. In these applications, the bleaching agent oxidizes various stains or soils on fabrics, textiles and hard surfaces.
Peroxygen bleaching compounds such as hydrogen peroxide, sodium percarborate and sodium perborate have been found useful in dry bleach formulations because of their oxidizing power. Other peroxygen compounds which supply oxidizing power include diacyl peroxides such as benzoyl peroxide.
Since peracids (the by-product of hydrolysis of the diacyl peroxide compounds) are difficult to stabilize and further since the peracids, if not stabilized, will attack enzymes and other compounds in solution susceptible to oxidative degradation, the oxidizing power of the diacyl peroxide compounds is protected by keeping them in the form of precursors.
Generally, the oxidizing power of the diacyl peroxide compound is released through the help of an activator in the wash. For example, activators such as perborate are known to react with benzoyl peroxides to result in the formation of perbenzoic acid.
A second way (other than bleach activators) of generating a peracid in the wash is to directly react an ester substrate (e.g., the peroxygen compound) with a perhydrolysis source. This mechanism is disclosed in EP 0,359,087. Such a perhydrolysis source is non-functional other than to activate the bleach precursor.
Another problem with this second approach is that the perhydrolysis source can itself destabilize other compounds of the composition.
Thus, the prior art teaches systems for generating peracids which either rely on expensive activators or which rely on supplying a non-functional and often destabilizing perhydrolysis source.
Accordingly, there is a need in the art for activating peroxygen source without using additional and expensive activator compounds and, preferably, with a compound which is already going to be used in the composition.
Further there is a need in the art for an activator compound which can release a peroxygen source under relatively mild conditions.
Unexpectedly, applicants have discovered a system whereby a peracid can be generated from a peroxygen source utilizing a component which will also be used for cleaning, i.e., an enzyme. The enzyme serves the dual purpose of activating the peroxygen source and providing detergent performance. Further, the enzyme has been found to activate under relatively mild pH conditions.
The present system may be used in liquid or powder detergent systems such as are well known to those skilled in the art.